I saw this after doing a quick Google search. Basically it looks like you have to stash the file online at a URL and link to it that way. I hope it helps, I don't use Google Earth on my phone:
"I got my Motorola Cliq's Google Maps to open both my private .kmz files and .kml files. Turned out the files are fetched from the Google server and not from the phone. So you must supply a publicly accessible URL to your file and it must not have password protection. Easiest place is the Google Earth Community but it stays there permanently, a privacy concern. I use Perl as a one time server for this use."
